It is proposed to analyze systematically the levels of adenylate kinase under different hemorrhagic shock situations. An attempt will be made to identify the organ(s) which release(s) this isoenzyme most readily during shock, and whether there is a relationship between these levels and the irreversibility of circulatory failure. The single withdrawal experiments will be compared with the standard Wiggers experimental shock technique in order to extrapolate the results. Finally, a new series of experiments will be initiated in which transmembrane potentials will be studied in the skeletal muscle during various phases of hemorrhagic shock. BIBLIOGRAPHIC REFERENCES: Zweifach, B.W. and Fronek, A.: The Interplay of Central and Peripheral Factors in Irreversible Hemorrhagic Shock, Progr. in Cardiovasc. Diseases, 18:147-180, 1975. Russell, P.J. and Fronek, A.: Adenylate Kinase Isoenzyme Levels During Reversible and Irreversible Hemorrhagic Shock in Cats, Fed. Proc. 35 (#3): 637, 1976.